INDIANAPOLIS -- New cars put new names at the top of the leaderboard in the opening weekend of practice for the 2012 Indianapolis 500.

For the time being, at least.

While the favored Penske and Ganassi teams laid low, a trio of young drivers stole the spotlight and set the pace at the famed Indianapolis Motor Speedway oval.

Sebastian Saavedra, a 21-year-old Colombian who has made 16 career Izod IndyCar Series starts over the past two years, ran a 221.526 mph lap Sunday afternoon in a Chevrolet-powered car run by Andretti Autosport.

Sebastian Saavedra turned the fastest lap of the weekend at opening practice for the Indy 500. Brian Spurlock/US Presswire

Perhaps more significantly, next up were two Americans with vastly different backgrounds, both driving for Sarah Fisher Hartman Racing.

Bryan Clauson, the first USAC driver to attempt to break into Indy cars for several years, and road racer Josef Newgarden, who is SFHR's full-time IndyCar Series driver, both topped 221 mph in their Honda-powered Dallara DW12s.

On Saturday, four of the top six speeds were by American drivers in their 20s -- and none of them were named Andretti or Rahal.

"There's a lot of good young guys coming up and I think that speaks volumes about the Mazda Road to Indy," remarked JR Hildebrand, another 20-something American who was seventh fastest after the first two days of practice. "There's a good crop of American drivers getting experience and winning races here in the U.S. at the lower levels, and that's what it's all about.

"Josef and I kind of graduated from that program in different ways, and that shows how well it does prepare you to come out here and do a good job."

Newgarden showed his field-topping performance on opening day wasn't a fluke by running P3 on Day 2.

The 21-year-old from Nashville has received positive remarks for his performances in 2012, including a daring (but unsuccessful) attempt to seize the lead from four-time series champion Dario Franchitti at the start of the Long Beach Grand Prix.

"The team has done a great job all year," Newgarden said. "They've built really good, reliable, comfortable race cars for me all year and they're doing the same for Bryan now. That makes our job really easy."

One theory being espoused about the youth movement at the top of the speed charts is that inexperienced teams and drivers don't have old bad habits to fall back on. The previous Dallara chassis was used from 2003 to 2011, and the top teams and drivers all knew precisely how it should feel or how it should react to changes.

With the new DW12 chassis and turbocharged V-6 engines, teams like Penske and Ganassi have just as much to learn about the package as smaller operations like SFHR and Dale Coyne Racing.

The Coyne team is another that has excelled so far in Indy practice, with Justin Wilson running fifth fastest and James Jakes in eighth.

"We had a good test here, we've got a good baseline setup and I'm really enjoying my time in it," said Wilson. "I think we're starting to understand this car better, and we'll keep chipping away the next seven days trying to get a little faster.

"Obviously everyone is nervous -- it's a new car. You're not sure what to expect and it takes time to work out the details and fine-tune it. But I think the speed will be there for qualifying."

The Penske and Ganassi teams were strangely subdued on the opening weekend, with Target Ganassi drivers Scott Dixon and Franchitti running only 36 and 39 laps, respectively.

Dixon was fourth fastest overall at 220.829 mph and the New Zealander turned a series of laps in the mid-218 mph range without the benefit of an aerodynamic tow.

"We're just making sure all the systems are working and everything is OK," Dixon said. "I think the car has speed in it, but until we get to Fast Friday and Pole Day, we really don't know who is going to be where."

Teams like Ganassi may be saving mileage on the one engine they are assigned to use for practice and qualifying. Each qualified car will receive a fresh engine for the race.

In addition, turbocharger boost pressure will be increased by approximately 8 percent for qualifying (from 130 to 140 kPa) by using the specification normally reserved for IndyCar's short oval races. Turbo boost will revert to superspeedway-spec 130 kPa for the race. Teams can practice with the increased boost level starting Friday morning.

The temporary boost increase is expected to create a bump of 40-50 horsepower in an effort to ensure a pole speed of at least 220 mph. Last year's pole speed was 227.8 mph; the record of 236.986 mph was set by Arie Luyendyk in 1996.

However, the change in power could also fundamentally change the handling balance of the cars and lead teams down blind alleys that might adversely affect their race preparation.

"It's Indy, and knowing that the weather looks good, it's easy to get carried away and try to do too many things too early," said Oriol Servia, who along with Dreyer & Reinbold Racing is also adjusting to running a Chevrolet engine after using a Lotus powerplant for the first four races of the season.

"We are just trying to pace ourselves to learn and make sure we do every step well. There are still things that we want to try, regardless of whether it's the right direction or not, just to see how it feels, since this is our first time in the DW12 on an oval."

The Lotus saga continues to be one of the less pleasant storylines during the month of May. Two teams have been released from their Lotus engine supply contracts, and Dragon Racing is suing for a release and $4.6 million in damages.

Dragon drivers Katherine Legge and Sebastien Bourdais have not logged any laps, and Legge's participation in the event is in jeopardy if there is not enough time for her to complete the mandatory rookie orientation program. Bourdais is being asked to take a refresher test because he has not competed at Indianapolis since 2005.

Jean Alesi's 209.438 mph effort is the best Lotus lap so far; cars must lap within 105 percent of the leader in order to qualify, or roughly 210 mph.

Simona De Silvestro has struggled to top 200 mph in her Lotus HVM Racing entry, the only other Lotus-powered car in the field.